River/Stream Decay Model Examples

Distributed Sources

This applet modeling is based on a first-order, at steady state, linear differential equation with constant parameters (flow, area, depth) over a given length:

where: 
S = Substance Concentration at x = x(t) (mg/L)
SD = Substance Distributed Concentration (mg//L)
K = Decay Constant (1/day)
t = Travel Time (day) = x / U
U = Stream Velocity (mi/day; mpd)
L = Distributed Source Length (mi)


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